The present invention relates to transfer lines for cryogenic fluids, of the type comprising, in an external tubular envelope, at least one internal tube for the transfer of fluid and at least one spacing member extending transversely between the tube and the envelope.
In the presently known techniques, the spacing members are generally of unpolished stainless steel and over-dimensioned to limit thermal loss by conduction.
The present invention has for its object to provide a fluid transfer line, and more particularly improved structures of spacing members permitting in a simple way and without significant increase of cost, reducing considerably the thermal losses.
To do this, according to one aspect of the invention, the spacing member has a polished external surface, typically by application of a layer of reflecting product.
According to other aspects of the invention:
the contact zones of the spacing member with the internal tube and the external envelope have an angular extent less than 90xc2x0, typically less than 60xc2x0, the contact zones with the tube on the one hand and with the envelope on the other hand being preferably angularly offset,
a portion of intermediate tube of material of low thermal conductivity is interposed between the spacing member and the internal tube, preferably with the interposition of a layer of insulating material between the portion of the intermediate tube and the internal tube.
The present invention also has for its object the use of such a cryogenic transfer line for the transfer of liquid helium.